Apparatus for heating fluids



Nov. 7,1944. v WALLI T AL. 2,362,107

APPARATUS, FOR HEATING FLUIDS Filed Jan. l8 1945 2 Sheets-Sheet l INVENTORS. (/0/7/7 51 14 6/03 Ja/m M4 777/0ckm0n42/7 APPARATUS FOR HEATING FLUIDS Filed Jan. 18, 1943 2 Sheets-Sheet 2 Patented Nov. 7,

APPARATUS FOR HEATING FLUIDS John s. Wallis, Darien, and John w. Throckmorton, Wilton, Coma, asslxnors to retro-Chem Process Company of Delaware Incorporated, a corporation Application January 18, 1943, Serial No. 472,076 r 3 Claims. (Cl. 122-356) Our invention relates to improvements in heaters and refers more particularly to a heater in which a. fluid is passed through a heating chamber in a plurality of separate streams in order to heat the fluid rapidly to a predetermined temperature, the design being such that not only is the temperature of the fluid rapidly and uniformly-attained but provision is also made for cooling'or quenching the fluid when i a given time period of heating has elapsed.

In the treatment of fluids, particularly in the petroleufn and chemicalindustries, there is'at v the present time an insistent demand for a heater in which fluids may be rapidly raised'to a high temperature (1000 to 15000 F.) and a heater in which such temperatures can be maintained for a predetermined period of time. Such requirements are not satisfied by a single coil in which the fluid is passed in a stream through a heating zone as the rate of. heat exchange between the combustion gases and fluid medium is not sufliciently'rapid to attain the desired temperatur 'within thetime period allowed, due to the difliculties in exposing suilicient surface of the fluid to the heatin gases.

Inthe heating of hydrocarbons or similar materials for the production of chemical products,

with or without the use of catalyst when temperatures are in' excess of 1000" F., the relationship between the heating surface, the reaction time and the heat transfer rates all become important and critical factors.

Such reactions reduction or arrestin zones may be more remote from the tube outlets, giving a longer time period before temperature quenching.

Our heater construction is designed to satisfy these requirements.

In the accompanying drawings which form 'a part of the instant specification and. are to be read in-conjunction therewith and in which ref-' erence numerals are used to indicate like parts in the various views,

Fig. 1- is a sectional elevational view,

Fig. 2 shows a developed section of the tubular heating elements,

Fig. 3 is a view taken along the line 33 in Fig. 1 in they direction of the arrows,

Fig. 4 is a view taken along the line 4-4 in Fig. 1 in the direction of the arrows,

Fig. ,5 is an elevational view of a modified type of heater with parts broken away,

Fig. 6 is a view taken along the line 5-6in Fig. 5 in the direction of the arrows, and

Fig. 7 is a view taken in the same location showing two streams of the heater connected by-means of a Y connection prior to being discharged in the accumulator.

Reierring to the drawings, in Figs. 1 and 5 the outer shell combustion chamber and flue construction are substantially the same. It consists of a vertical casing l0 lined with insulation II and fire resistant lining such as silocel, carborundum'. brick or other type of fire resistant magenerally requir minimum time under tempera- I ture, which necessitates the use of small tubes, low pressure drop, high transfer rate, and a multiplicityv of passes through the heating zone. In addition, it is advantageous, in some instances, to reduce the temperatureas quickly as possible upon discharge from the heating zone.

For example, a furnace employing 4" tubes as compared with a, furnace having double the number of 2'f tubes has approximately the same heating surface; but the volume or time of reaction is reduced by one-half. 7

Our invention provides a'heater having a plu-' 'rality of passes of small diameter heatexchange tubes so disposed that each pass absorbs the same amount of heat. It also becomes important, in

' some types of processing, to reduce the temperature of materials being heated-immediately upon reaching a predetermined temperature, so that the materials being heated are subjected to a rising temperature gradient from the inlet to' the pointv where the temperature is arrested.

, In other cases, the location of the temperature terial shown at l2. The chamber is fired by 111- rectional burners diagrammatically shown at I3. The'heater is supported onsuitable standards or legs shown at H. In the upper part of the combustion chamber is a baiile I5 which diverts the combustion gases outwardly near the top of the heater and increases thev heat exchange between the cooler combustion gases and the tubes in that section of the heater. On the upper portion of the tubes adjacent the baiile and where the tubes are subjected principally to convection heat, extended surfaces may be used although this detail has been omitted from the drawings in the interest of simplicity.

The novelty of the construction lies principally in the arrangement-of the tube sections within a cylindrical heater and the mannerin which they are connected to the inlet and outlet manifolds. chamber are of secondary importance. Atthe top of the heater is a breeching l6 surmounted by a chimney or stack H.

In both types of construction shown in Figs. 1 and 5 near the top of theheater is a circular The construction details of the heating manifold It to which fluid may be introduced through pipes It. The number of these inlet pipes will depend upon the size of the heater and the rate at which it is desired to introduce fluid .to the tubes.' Within the cylindrical heating chamber and arranged around the inside surface or wall l2 are a plurality of vertical tube sections 20. The one extremity of each tube section is connected to the manifold l8, as shown in Fig. 2. Each of the tube-sections consists of a plurality of vertical passes joined by return bends, as shown in Fig. 2.

- In the construction shown in Figs. 1 to 4, in-

elusive, the opposite ends of the individual tube sections fromthose connected to the manifold l8 are joined top. bottom manifold 2|. Outlet pipes 22 are connected to this'bottom manifold to draw off the heated liquids. These -outlet or withdrawal pipes may be located at any suitable points around the periphery of manifold 2|. At intervals on the circumference of the lower manifold or above the manifold where the tube sections leave the heating chamber are connected inlet pipes 23, as shown in Figs. 2 and 4, which provide means for introducing a cooling or quenching fluid to the fluid being heated. In the modified construction shown in Figs. 5 and 6 in place of a lower circular manifold M an accumulator or tank 24 is used. Into this accumulator are connected the discharge ends of the separate tube sections. A cooling or quenching fluid may be introduced to the accumulator through pipe 25 and in the event that a single pipe is insufficient to supply an adequate amount of cooling fluid, a plurality of pipesmay be used. Discharge from the accumulator is through pipe 26. In the modification shown in Fig. '1 the discharges from two of the tube sections 20 are combined in a single pipe which flows ino the accumulator 24. By this modification the fluid from two of the pipe sections is combined before entering the accumulator.

The flow ,of fluid through the heater shown in Figs. 1 to 4, inclusive, would be as follows: Fluid to be heated is introduced through inlet pipes l9 connected to manifold l8. This manifold or distribuor directs the fluid to the individual tube sections 20 through which the fluid is circulated through the heating space within' the furnace. During its passage through tubes 20 the fluid is subjected to both radiant and convection heat and the temperature rapidly brought to the desired point. The fluid is discharged into the lower manifold 2| from which it may be withdrawn. When cooling or quenching of the heated fluid is desired cooling fluid is introduced through pipes 23 above the manifold 2| or through pipes designated by the same number connected into the manifold.

In the construction shown in Figs.-5to 7, inclusive, fluid introduced through pipes 19 passes through manifold l8 down through the separate tube sections 20 from which it is discharged into an accumulator 24. From the accumulator it is withdrawn through pipe 26 either in highly heated form or in cooled condition due to mixture with the cooling fluid introduced to the accumulator through pipe 25.

Man indication of the wide difference in results obtained by varying the-furnace design, the length of travel of the fluid during heating, the time of cooling or quenching and other critical factors related thereto, we offer the following typical example:

When petroleum naphtha was heated to 1350 recovered. When the same charging stock was used and 4" tubes having the same heating surface were employed in a furnace of the same design there was obtained approximately 40% consub-combinations. This contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in de-"- tails with the scope of Our claims without departing from the spirit of our invention. It is thereforeto be understood that our invention is not to be limited to the specific details shown and described.

Having thus described our invention, we claim:

1. A heater construction comprising a cylindrical combustion chamber, a heat source within said chamber, vertical tube banks located adjacent the combustion chamber wall having inlet and outlet ends, an inlet distributor at the top and outside of the combustion chamber and an outlet accumulator, in the bottom, and located outside the combustionchamber said inlet ends connected to the distributor and said outlet ends connected to the accumulator, means for introducing fluid into said distributor, means for withdrawing heated fluids from said accumulator and means for introducing a quenching medium adjacent the outlet ends of said tube banks.

2. A heater construction comprising a cylindrical combustion chamber, a heat source within said chamber, vertical tube banks located adjacent the combustion chamber wall having inlet and outlet ends, an inlet distributor at the top and outside of the combustion chamber and an outlet accumulator, in the bottom, and located outside the combustionchamber said inlet ends connected to the distributor and said outlet ends connected to the accumulator, means for introducing fluid into said distributor, means for withdrawing heated fluids from said accumulator, and means for introducing a quenching medium to the accumulator.

3. A heater construction comprising a cylindrical combustion chamber, a heat source within said chamber, vertical tube, banks located adjacent the combustion chamberwall having inlet and outlet ends, an inlet distributor at the top and outside of the combustion chamber and an outlet accumulator, in the bottom, and located outside the combustion chamber, said inlet ends connected tothe distributor and said outlet ends connected to the accumulator, means for intro"v ducing fluid into said distributor, means for withdrawing heated fluids from said accumulator, and means for introducing a quenching medium into the outlet ends of each tube bank ahead of their connection to the accumulator.

JOHN S. WALLIS.

JOHN W. THROCKMORTON. 

